Automatic retries

Sometimes requests fail. When these requests fail for transient issues, Emissary can automatically retry the request.

Retry policy can be set for all Emissary mappings in the ambassador Module, or set per Mapping. Generally speaking, you should set retry_policy on a per mapping basis. Global retries can easily result in unexpected cascade failures.

Note that when setting retry_policy, adjusting max_retries in the circuit breaker configuration should also be considered in order to account for all desired retries.

Configuring retries

The retry_policy attribute configures automatic retries. The following fields are supported:

retry_policy:
  retry_on: <string>
  num_retries: <integer>
  per_try_timeout: <string>

retry_on

(Required) Specifies the condition under which Emissary retries a failed request.

For more details on each of these values, see the Envoy documentation.

num_retries

(Default: 1) Specifies the number of retries to execute for a failed request.

per_try_timeout

(Default: global request timeout) Specify the timeout for each retry. Must be in seconds or nanoseconds, e.g., 1s, 1500ns.

Examples

A per mapping retry policy:

---
apiVersion: getambassador.io/v3alpha1
kind:  Mapping
metadata:
  name:  quote-backend
spec:
  hostname: '*'
  prefix: /backend/
  service: quote
  retry_policy:
    retry_on: "5xx"
    num_retries: 10

A global retry policy (not recommended):

---
apiVersion: getambassador.io/v3alpha1
kind:  Module
metadata:
  name:  ambassador
spec:
  config:
    retry_policy:
      retry_on: "retriable-4xx"
      num_retries: 4
---
apiVersion: getambassador.io/v3alpha1
kind:  Mapping
metadata:
  name:  quote-backend
spec:
  prefix: /backend/
  service: quote
  hostname: '*'